SPECKLED ALDER - ALNUS INCANA

Common Name: speckled alder

Scientific Name: 
Family: Betulaceae
Genus: Alnus
Species: incana

Hardiness Zone: 2 to 6
Height: 15 to 25 ft
Width: 15 to 25 ft

 

Common characteristics:

Speckled alder is most often seen in a multi-trunked form to 15-25' tall with a broad-rounded irregular crown. Often used as a thicket for erosion control. The bark of these trees are brown to reddish-brown to grayish, with scattered white lenticels (pores), older bark is grayish to reddish-brown with pale horizontal lenticels (pores). Leaves are alternate and simple 1" to 4" in length, egg-shaped with acuminate tips. The edges are coarsely doubly toothed with shallow lobes. The upper surface of leaves are dark green while the lower surface is dull green and hairy, especially along the veins.

The speckled alder is monoecious meaning male and female flowers are borne separately on the same plant. They are formed in clusters called catkins, blooming in very early spring before leaves emerge.

Where it grows:

Grows well in moist, well-drained soils. Will tolerate wet sites that experience occasional flooding as well as dry sites. Best in full sun to partial shade. 

How it’s used:

A fast-growing and flood-tolerant species that is short-lived, rarely exceeding 40 years. It can be thicket-forming and provides erosion control along watercourses in the mountains. Alders fix nitrogen and thus serve as nutrient-giving pioneers in reclamation projects. Can be used in the urban setting in residential or park settings and under powerlines. 

Ecosystem services:

Used as browse by small and game mammals.  

Where it is native to:

 Native throughout the United States, except through the plains states and the south to the southeastern region of the country. Common through all of Minnesota. 

Problems:

No serious insect or disease problems are known. Canker can be severe and powdery mildew and leaf curl may appear. Be watchful for aphids, leaf miners, tent caterpillars, lace bugs, and flea beetles. 

References:

Minnesota Wildflowers. (Alnus incana) Found Online: https://www.minnesotawildflowers.info/shrub/speckled-alder

Missouri Botanical Garden. (Plant Finder) Found Online: http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=277838&isprofile=1&basic=Alnus%20incana

The Morton Arboretum. (Trees & Plants) Found Online: https://www.mortonarb.org/trees-plants/tree-plant-descriptions/speckled-alder

Lady Bird Johnson Wildflower Center. (Plant Database) Found Online: https://www.wildflower.org/plants/result.php?id_plant=ALIN2

speckled alder bark
speckled alder foliage
speckled alder bud
speckled alder
speckledalder-fruit
speckled alder fruit
speckled alder cone